#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	n/=10;
	if(n>=9) cout<<"A";
	else if(8<=n&&n<9) cout<<"B";
	else if(7<=n&&n<8) cout<<"C";
	else if(6<=n&&n<7) cout<<"D";
	else cout<<"E";
    return 0;
}

